This report describes the typical weather at the Sky Harbor Airport (Duluth, Minnesota, United States) weather station over the course of an average January. It is based on the historical records from 2001 to 2012. Earlier records are either unavailable or unreliable.
Duluth, Minnesota has a humid continental climate with warm summers and no dry season. The area within 25 mi of this station is covered by croplands (34%), forests (30%), oceans and seas (18%), grasslands (13%), and lakes and rivers (3%).
The month of January is characterized by gradually falling daily high temperatures, with daily highs ranging from 28°F to 24°F over the course of the month, exceeding 39°F or dropping below 9°F only one day in ten.
Over the course of January, the length of the day is gradually increasing. From the start to the end of the month, the length of the day increases by 58 minutes, implying an average day-over-day increase of 1.9 minutes.
The shortest day of the month is January 1 with 8:38 hours of daylight; the longest day is January 31 with 9:35 hours of daylight.
The earliest sunrise is at 7:35am on January 31; the latest sunset is at 5:10pm on January 31; the latest sunrise is at 7:53am on January 2; the earliest sunset is at 4:30pm on January 1.
Daylight savings time is observed in 2012 but it neither starts nor ends in January, so the entire month is in standard time.
The median cloud cover ranges from 59% (partly cloudy) to 74% (partly cloudy). The trend is for the sky to be clearing with the median cloud cover decreasing by 14% from the start to the end of the month.
On January 31, the clearest day of the month, the sky is clear, mostly clear, or partly cloudy 44% of the time, and overcast or mostly cloudy 45% of the time.
On January 3, the cloudiest day of the month, the sky is overcast, mostly cloudy, or partly cloudy 59% of the time, and clear or mostly clear 35% of the time.
The probability that precipitation will be observed at this location varies throughout the month. Precipitation is most likely around January 2, occurring in 47% of days. Precipitation is least likely around January 31, occurring in 43% of days.
Throughout January, the most common forms of precipitation are light snow and moderate snow.
Light snow is the most severe precipitation observed during 50% of those days with precipitation. It is most likely around January 1, when it is observed during 25% of all days.
Moderate snow is the most severe precipitation observed during 37% of those days with precipitation. It is most likely around January 31, when it is observed during 18% of all days.
The likelihood of snow falling is highest around January 2, occurring in 41% of days.
Either snow rarely accumulates at this location in January or snow depth measurements are unavailable or unreliable.
The relative humidity typically ranges from 58% (mildly humid) to 88% (very humid) over the course of a typical January, rarely dropping below 40% (comfortable) and reaching as high as 98% (very humid).
The air is driest around January 31, at which time the relative humidity drops below 69% (mildly humid) three days out of four; it is most humid around January 1, rising above 82% (humid) three days out of four.
Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.
Over the course of a typical January, the dew point typically varies from 1°F (dry) to 21°F (dry) and is rarely below -18°F (dry) or above 33°F (dry).
Over the course of January typical wind speeds vary from 1 mph to 17 mph (light air to moderate breeze), rarely exceeding 24 mph (fresh breeze).
The highest average wind speed of 9 mph (gentle breeze) occurs around January 19, at which time the average daily maximum wind speed is 16 mph (moderate breeze).
The lowest average wind speed of 9 mph (gentle breeze) occurs around January 28, at which time the average daily maximum wind speed is 16 mph (moderate breeze).